Reactor microbalance

Fig. 10. Microbalance reactor for operation over an extended temperature range — 195°C. to 1000°C. [After Gulbransen and Andrews, private communication (1952).]...

Fig. 13. Microbalance reactor for use with getters of evaporated metal films formed in situ. [After Rhodin, J. Phys. Colloid Chem., to be published in 1953.]...

Characterization of Catalysts under Working Conditions with an Oscillating Microbalance Reactor... 

Fig. 1. The tapered element oscillating microbalance reactor manufactured by Patashnick and Rupprecht (TEOM Series 1500 PMA Reaction Kinetics Analyzer). The term Cat. refers to the catalyst sample.

All pyrolysis experiments were carried out in the thermo-gravimetric apparatus (TGA) having a pressure capacity of up to 1000 psi. A schematic of the experimental unit is shown in Figure 1. It consists of the DuPont 1090 Thermal Analyzer and the microbalance reactor. The latter was enclosed inside a pressure vessel with a controlled temperature programmer and a computer data storage system. The pressure vessel was custom manufactured by Autoclave Engineers. A similar set-up was used previously by others.( )... 

The products of the pyrolysis are grouped under three categories a gas phase material, a distillable liquid, and a nondistillable char, all at ambient conditions. At any time during the course of the reaction, the material in the microbalance reactor would be a combination of the incompletely reacted pitch and the char reaction product, which will be referred to as the residue. 

In contrast, a literature model [16] contains 14 reactions, since it allows almost all possible (reversible) reactions between lumps. By feeding toluene and hydrogen to the microbalance, we find that toluene is virtually unreactive, indicating that there are no reverse reactions from toluene to nCv and iC . Consider another literature model in which there is neither direct nC dehydrocyclization to toluene (k2 = 0) nor direct nC7 cracking [5]. Using this literature model, we can find a set of k s that would fit our fixed-bed data over a limited range of conditions. However, the new ke and do not even come close to describing the ECP-feed differential microbalance reactor data. 

The principles of flow microbalance reactors were described in a previous paper (.3). The present experiments were performed in the equipment shown in Figure 1. 

As far as the growth mechanism of CNFs is concerned, pioneering works by Lobo et al. [33] and Baker and co-workers [34] were based on two different techniques, allowing the process to be monitored continuously a microbalance reactor [33] and controlled-atmosphere electron microscopy [34]. The former technique allowed for detailed kinetic measurements, from which a mechanism was proposed that involved the detachment of metal particles from the support, carbon growing beneath these particles and pushing them away from the surface. Observations of Baker have clearly confirmed this mechanism. These early studies [33-36] mark three important steps after hydrocarbon decomposition... 

Hershkowitz, F., and Madiara, P.D., Simultaneous measurement of adsorption, reaction, and coke using a pulsed microbalance reactor, Ind. Eng. Chem. Res., 32(12), 2969-2974 (1993). 

It is impossible to comprehensively discuss all non-vibrational in situ techniques with a potential application to oxidation catalysts within this chapter. Therefore, we have selected only those methods for a more detailed presentation which have seen a widespread application so far and/or offer unique opportunities for understanding the functioning of real catalysts. For more specific in situ methods, such as the microscopy techniques mentioned above, Mossbauer spectroscopy which is restricted to the viewing of elements only, or thermo-analytical studies using an oscillating microbalance reactor,the reader is referred to the respective reviews. 

Chen, D., Bjorgum, E., Christensen, K., etal. (2007). Characterization of Catalysts underworking Conditions with an Oscillating Microbalance Reactor, Adv. Catal., 51, pp. 351-382. 

---